I always get the same color formula at the salon but my color came out brassy.?

I have been going to the same salon for years and have been getting the same formula of Wella hair color to make my hair a natural light blonde color. I had the same colorist do it for years and always had great results. He then moved away, so I tried a new salon that was closer but they did a terrible job and made... show more I have been going to the same salon for years and have been getting the same formula of Wella hair color to make my hair a natural light blonde color. I had the same colorist do it for years and always had great results. He then moved away, so I tried a new salon that was closer but they did a terrible job and made it super brassy. I then went back to the original salon that had the formula my old colorist used in my file and had another hairstylist who was very experienced do my hair with that same formula. It came out just as beautiful as it had with my old stylist and was not at all brassy. Because I now live very far from the salon and because money has been very tight I went a whole seven months without a haircut or root touch up. I finally got it done today (with the same formula) and it looked beautiful in the salon. However, when I got home it looked very different in that lighting and it was super orange and brassy. I am not sure what went wrong. Did she mess up the formula? Were the thirty-five minutes she left it in for not long enough or was it because my hair was so grown out it was not as easy to lift had it been just the roots? How do I fix it? Would a purple shampoo or toner cool it down or will I have to go back?